Those pesky windows buttons (maximise, minimise and close) default to the left of the menu bar after a new Ubuntu installations, and it’s been happening since 10.04. Most people, like myself, are stuck in our ways and just want them back where they belong. It’s pretty easy to do this, just open up a terminal (ctrl+alt+t) and copy in the following:
gconftool -s /apps/metacity/general/button_layout -t string menu:minimize,maximize,close
Once you hit enter, you should see the buttons return to their rightful place on the right, also in the right order.